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plugins/mod_invites_register.lua @ 13801:a5d5fefb8b68 13.0

mod_tls: Enable Prosody's certificate checking for incoming s2s connections (fixes #1916) (thanks Damian, Zash) Various options in Prosody allow control over the behaviour of the certificate verification process For example, some deployments choose to allow falling back to traditional "dialback" authentication (XEP-0220), while others verify via DANE, hard-coded fingerprints, or other custom plugins. Implementing this flexibility requires us to override OpenSSL's default certificate verification, to allow Prosody to verify the certificate itself, apply custom policies and make decisions based on the outcome. To enable our custom logic, we have to suppress OpenSSL's default behaviour of aborting the connection with a TLS alert message. With LuaSec, this can be achieved by using the verifyext "lsec_continue" flag. We also need to use the lsec_ignore_purpose flag, because XMPP s2s uses server certificates as "client" certificates (for mutual TLS verification in outgoing s2s connections). Commit 99d2100d2918 moved these settings out of the defaults and into mod_s2s, because we only really need these changes for s2s, and they should be opt-in, rather than automatically applied to all TLS services we offer. That commit was incomplete, because it only added the flags for incoming direct TLS connections. StartTLS connections are handled by mod_tls, which was not applying the lsec_* flags. It previously worked because they were already in the defaults. This resulted in incoming s2s connections with "invalid" certificates being aborted early by OpenSSL, even if settings such as `s2s_secure_auth = false` or DANE were present in the config. Outgoing s2s connections inherit verify "none" from the defaults, which means OpenSSL will receive the cert but will not terminate the connection when it is deemed invalid. This means we don't need lsec_continue there, and we also don't need lsec_ignore_purpose (because the remote peer is a "server"). Wondering why we can't just use verify "none" for incoming s2s? It's because in that mode, OpenSSL won't request a certificate from the peer for incoming connections. Setting verify "peer" is how you ask OpenSSL to request a certificate from the client, but also what triggers its built-in verification.
author Matthew Wild <mwild1@gmail.com>
date Tue, 01 Apr 2025 17:26:56 +0100
parent 13011:16b47c3b44f3
child 13843:87dd8639f08f
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local st = require "prosody.util.stanza";
local jid_split = require "prosody.util.jid".split;
local jid_bare = require "prosody.util.jid".bare;
local rostermanager = require "prosody.core.rostermanager";

local require_encryption = module:get_option_boolean("c2s_require_encryption",
	module:get_option_boolean("require_encryption", true));
local invite_only = module:get_option_boolean("registration_invite_only", true);

local invites;
if prosody.process_type == "prosody" then
	invites = module:depends("invites");

	if invite_only then
		module:depends("register_ibr");
	end
end

local legacy_invite_stream_feature = st.stanza("register", { xmlns = "urn:xmpp:invite" }):up();
local invite_stream_feature = st.stanza("register", { xmlns = "urn:xmpp:ibr-token:0" }):up();
module:hook("stream-features", function(event)
	local session, features = event.origin, event.features;

	-- Advertise to unauthorized clients only.
	if session.type ~= "c2s_unauthed" or (require_encryption and not session.secure) then
		return
	end

	features:add_child(legacy_invite_stream_feature);
	features:add_child(invite_stream_feature);
end);

-- XEP-0379: Pre-Authenticated Roster Subscription
module:hook("presence/bare", function (event)
	local stanza = event.stanza;
	if stanza.attr.type ~= "subscribe" then return end

	local preauth = stanza:get_child("preauth", "urn:xmpp:pars:0");
	if not preauth then return end
	local token = preauth.attr.token;
	if not token then return end

	local username, host = jid_split(stanza.attr.to);

	local invite, err = invites.get(token, username);

	if not invite then
		module:log("debug", "Got invalid token, error: %s", err);
		return;
	end

	local contact = jid_bare(stanza.attr.from);

	module:log("debug", "Approving inbound subscription to %s from %s", username, contact);
	if rostermanager.set_contact_pending_in(username, host, contact, stanza) then
		if rostermanager.subscribed(username, host, contact) then
			invite:use();
			rostermanager.roster_push(username, host, contact);

			-- Send back a subscription request (goal is mutual subscription)
			if not rostermanager.is_user_subscribed(username, host, contact)
			and not rostermanager.is_contact_pending_out(username, host, contact) then
				module:log("debug", "Sending automatic subscription request to %s from %s", contact, username);
				if rostermanager.set_contact_pending_out(username, host, contact) then
					rostermanager.roster_push(username, host, contact);
					module:send(st.presence({type = "subscribe", from = username.."@"..host, to = contact }));
				else
					module:log("warn", "Failed to set contact pending out for %s", username);
				end
			end
		end
	end
end, 1);

-- Client is submitting a preauth token to allow registration
module:hook("stanza/iq/urn:xmpp:pars:0:preauth", function(event)
	local preauth = event.stanza.tags[1];
	local token = preauth.attr.token;
	local validated_invite = invites.get(token);
	if not validated_invite then
		local reply = st.error_reply(event.stanza, "cancel", "forbidden", "The invite token is invalid or expired");
		event.origin.send(reply);
		return true;
	end
	event.origin.validated_invite = validated_invite;
	local reply = st.reply(event.stanza);
	event.origin.send(reply);
	return true;
end);

-- Registration attempt - ensure a valid preauth token has been supplied
module:hook("user-registering", function (event)
	local validated_invite = event.validated_invite or (event.session and event.session.validated_invite);
	if invite_only and not validated_invite then
		event.allowed = false;
		event.reason = "Registration on this server is through invitation only";
		return;
	elseif not validated_invite then
		-- This registration is not using an invite, but
		-- the server is not in invite-only mode, so nothing
		-- for this module to do...
		return;
	end
	if validated_invite and validated_invite.additional_data and validated_invite.additional_data.allow_reset then
		event.allow_reset = validated_invite.additional_data.allow_reset;
	end
end);

-- Make a *one-way* subscription. User will see when contact is online,
-- contact will not see when user is online.
function subscribe(host, user_username, contact_username)
	local user_jid = user_username.."@"..host;
	local contact_jid = contact_username.."@"..host;
	-- Update user's roster to say subscription request is pending...
	rostermanager.set_contact_pending_out(user_username, host, contact_jid);
	-- Update contact's roster to say subscription request is pending...
	rostermanager.set_contact_pending_in(contact_username, host, user_jid);
	-- Update contact's roster to say subscription request approved...
	rostermanager.subscribed(contact_username, host, user_jid);
	-- Update user's roster to say subscription request approved...
	rostermanager.process_inbound_subscription_approval(user_username, host, contact_jid);
end

-- Make a mutual subscription between jid1 and jid2. Each JID will see
-- when the other one is online.
function subscribe_both(host, user1, user2)
	subscribe(host, user1, user2);
	subscribe(host, user2, user1);
end

-- Registration successful, if there was a preauth token, mark it as used
module:hook("user-registered", function (event)
	local validated_invite = event.validated_invite or (event.session and event.session.validated_invite);
	if not validated_invite then
		return;
	end
	local inviter_username = validated_invite.inviter;
	local contact_username = event.username;
	validated_invite:use();

	if inviter_username then
		module:log("debug", "Creating mutual subscription between %s and %s", inviter_username, contact_username);
		subscribe_both(module.host, inviter_username, contact_username);
		rostermanager.roster_push(inviter_username, module.host, contact_username.."@"..module.host);
	end

	if validated_invite.additional_data then
		module:log("debug", "Importing roles from invite");
		local roles = validated_invite.additional_data.roles;
		if roles and roles[1] ~= nil then
			local um = require "prosody.core.usermanager";
			local ok, err = um.set_user_role(event.username, module.host, roles[1]);
			if not ok then
				module:log("error", "Could not set role %s for newly registered user %s: %s", roles[1], event.username, err);
			end
			for i = 2, #roles do
				local ok, err = um.add_user_secondary_role(event.username, module.host, roles[i]);
				if not ok then
					module:log("warn", "Could not add secondary role %s for newly registered user %s: %s", roles[i], event.username, err);
				end
			end
		elseif roles and type(next(roles)) == "string" then
			module:log("warn", "Invite carries legacy, migration required for user '%s' for role set %q to take effect", event.username, roles);
			module:open_store("roles"):set(contact_username, roles);
		end
	end
end);

-- Equivalent of user-registered but for when the account already existed
-- (i.e. password reset)
module:hook("user-password-reset", function (event)
	local validated_invite = event.validated_invite or (event.session and event.session.validated_invite);
	if not validated_invite then
		return;
	end
	validated_invite:use();
end);